Acrylonitrile-butadiene rubbers are known as rubbers having favorable properties of oil resistance, abrasion resistance, and aging resistance, and are used for, for example, oil-resistant products such as oil seals, gaskets, oil-resistant hoses, conveyor belts, printing rolls, and top rolls for spinning. Acrylonitrile-butadiene rubbers, however, are inferior in properties such as non-stickiness and heat resistance, and are thus desired to be improved in some uses.
Meanwhile, fluororesins have excellent properties such as slidability, heat resistance, chemical resistance, solvent resistance, weather resistance, flexibility, electric properties, and non-stickiness, and are thus used in broad fields such as automobiles, industrial machines, OA equipment, and electrical and electronic equipment. Fluororesins have particularly excellent slidability, and have a low friction coefficient which is outstanding among the resins. Fluororesins, however, are inferior to crystalline heat resistant thermoplastic resins in terms of physical properties such as mechanical properties and load deflection temperature in many cases, and are therefore limited in their use.
One way to deal with this problem is improving these properties by combination use of the rubber and the resin.
For example, Patent Literature 1 discloses an oil seal including a low-stickiness elastic coating layer that is formed by dissolving as a main component an unvulcanized fluororubber, an unvulcanized acrylic rubber, or an unvulcanized nitrile rubber, and applying an organic solvent-type rubber cement in which fluororesin powder is dispersed.
Patent Literature 2 discloses a lubricating rubber composition obtained by mixing a diene-based rubber, a thermoplastic fluororesin, and a low molecular weight fluoropolymer having an average molecular weight of 50000 or lower.
Patent Literature 3 discloses a thermoplastic polymer composition formed from a fluororesin (A) and a non-fluorinated crosslinked rubber (B), wherein the fluororesin (A) contains a fluoroethylenic polymer (a), and the non-fluorine crosslinked rubber (B) is obtained by crosslinking at least part of at least one rubber (b).